Abstract
Operation reliability of NPP I&C and its components is considered in this chapter. Besides quantitative measures, qualitative features that provide required functional reliability such as protection against Common Cause Failures (CCF), single-failure criterion, redundancy, diversity, prevention of personnel errors, and technical diagnostics, are discussed. A group of features of NPP I&C and its components, united by “performance resistance,” is also considered. In particular, they are resistance to environment influences, mechanical influences (including earthquake impacts), insensitivity changes of power supply, and electromagnetic disturbances. Operation quality issues are considered. By quality (in a broad sense), the authors mean the accuracy, response rate characteristics, and features of human-machine interfaces. Features that provide NPP I&C independence from malfunction or removal from operation of system components (including redundant ones) or from adjacent NPP I&C, and the decrease of possible impact of components on other adjacent systems (electromagnetic emission, fire safety) are described as well.
TopIntroduction
The steadily growing role of up-to-date instrumentation and control (I&C) systems that assure NPP safety and security requires that:
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Properties of each I&C system and its components (hardware and software) at all life cycle stages should meet requirements of national and international regulations, rules and standards of nuclear safety.
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A procedure of development, design, manufacturing, testing, acceptance and operation of the system and its components determined by regulations, rules and standards of nuclear safety should be observed. for each I&C system.
IEC standard 61508 (IEC, 2008) interprets compliance with the indicated requirements as functional safety of I&C system.
The object of the chapter – is to show those general properties of I&C systems and their central equipment (software-hardware complex - SHC) and peripheral equipment, used during NPP automation, that provide functional safety of these systems.
TopBackground
Experience of international society in NPP safety assurance, including functional safety of I&C systems, accumulated in requirements of national and international regulations, rules and standards of nuclear safety and was considered during the large-scale modernization, carried out at all Ukrainian NPPs within programs of safety improvement and extension of service life of operating power units. These activities contributed to accumulation of Ukrainian own experience in standardization, assurance and assess of functional safety (further – safety) of I&C systems, implemented using up-to-date technologies, modern electronic components and computing technology, optic communication networks, computer facilities for diagnostic, display, archiving, etc.
The properties of safety important I&C systems and their components that are described further are determined by the applied requirements (Figure 1):
Figure 1. Rules, regulations, and standards governing the properties of I&C systems and their components
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Regulations, rules and standards of nuclear and radiation safety in force in Ukraine (NP, 1999; NP, 2000; NP, 2003,a; NP, 2003,b; NP, 2005; NP, 2008,a; NP, 2008, b; NAPB, 2000; PNAE, 1987).
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Safety standards of the International Atomic Energy Agency (IAEA, 2000; IAEA, 2002,a; IAEA, 2011, a; IAEA, 2012).
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Standards of the International Electrotechnical Commission, applicable to Instrumentation and control systems, important to NPPs safety (IEC, 1996; IEC, 1998; IEC, 2005, a; IEC, 2007,a; IEC, 2007, b; IEC, 2011).
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International industrial standards (IEC, 2001,a - IEC 2001,g, IEC 2002, a- IEC 2002,c IEC 2004, IEC 2005,b; IEC 2006,a; International Special Committee on Radio Interference- CISPR 2006, ISO 2000).
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State standards of Ukraine (DSTU ІЕС, DSTU CISPR, DSTU ISO), identical with relevant international standards.
Conformance to requirements of these documents, reflecting long-term national and foreign experience in standardization, assurance and assessment of safety of systems and their components applied in NPP, was supervised by State Nuclear Regulatory Authority of Ukraine and considered as one of the main conditions for issuing a permit for manufacturing and implementation of safety important I&C systems.